1. Technical Field
The invention is generally directed to wireless communication systems and more specifically, to a reference signal (RS) transmission scheme.
2. Background Art
Description of RS Patterns for Long Term Evolution (LTE)/Long Term Evolution Advanced (LTE-A) and User Equipment (UE) Channel State Information (CSI) feedback.
In communication systems, Reference Signals (RSs) are predefined symbols which are embedded in the data symbols at the transmitter. Based on the received RSs, the receiver can estimate the channel and feedback the channel state information (CSI) to the transmitter such that it can perform link adaptation accordingly. In particular, for a LTE/LTE-A system, the cell-specific RSs (CRSs) are embedded in a time-frequency two-dimensional lattice. 3GPP TS 36.211 is an example of a system implementing cell-specific RSs (CRSs).
Montojo et al, (US Patent Publication No. 2010/0075706 A1) shows an example of systems and methodologies of creating antenna ports to correspond to two or more groups of user equipment (UEs). Such systems may organize two or more groups of UEs and create a respective antenna port for each of the two or more groups of UEs.